Heat exchanger construction



Oct. 29, 1968 M. L. RYALL 3,407,873

v HEAT EXCHANGER CONSTRUCTION 'l l Filed Aug. l, 1966 5 Sheets-Sheet 1 Oct. 29, 1968 l M. n.. RYALL 3,407,873,

4 HEAT EXCHANGER CONSTRUCTION Filed Aug. 1, 1966 5 Sheets-Sheet 2 Oct. 29, 1968 M, L, RYALL 3,407,873

HEAT EXCHANGER CNSTRUGTION Filed Aug. 1. 1966 5 Sheets-Sheet 3 I-H lnuenlor A Harney;

Oct. 29, 1968 M. L. RYALL HEAT EXCHANGER CONSTRUCTION 5 Sheets-Sheet 4 Filed Aug. l. 1966 Inventor MICHAEL Lesue PYALL- masomwwliy ttorneys Oct. 29, 1968 M, 1 RYALL 3,407,873

HEAT EXCHANGER CONSTRUCTION Filed Aug. 1. 1966 5 Sheets-Sheet 5 Harney;

United States Patent O m 3,407,873 HEAT EXCHANGER CONSTRUCTION Michael Leslie Ryall, Cathcart, Glasgow, Scotland, as-

ABSTRACT OF 'THE DISCLOSURE A heat exchanger has a shell which is closed at both ends, at one end by a toroidal header comprised of two annular sections. The header has an annular bore therein and inlet and outlet ports are provided on the header for uid to be heated connecting with said bore. The annular sections are joined at two pairs of annular adjoining surfaces which are arranged such that they lie together with the centre line of the bore on an imaginary frustoconical surface, the annular sections being joined by welding at the sections to form a unitary assembly. U-tubes for the through flow for the fluid to be heated extends into the shell and have inlets and outlets in communication with the bore. Baffie plates are provided in the bore to separate the inlets of the tubes from the outlets from the tubes and an inlet and an outlet are provided for heating uid to the shell.

This invention relates to she1l-andtube heat exchangers having a shell with a header at one end, and conduit means extending from the header into the shell, such heat exchangers being referred to hereinafter as heat exchangers of the type aforesaid.

According to the present invention a heat exchanger comprises a shell having at one end a toroidal header with an annular bore therein and comprised of two annular sections, the two pairs of annular adjoining surfaces at which the annular sections are joined being arranged such that they lie together with the centre line of the bore on an imaginary frusto-conical surface severing the header, the annular sections being joined by welding at the surfaces to form a unitary assembly, inlet and outlet ports on the header for fiuid to be treated in communication with said bore, conduit means mounted on the header and extending into the shell, the conduit means having inlet and outlet openings in communication with the bore, bafe plates within the bore to separate the inlet to the conduit means from the outlet, from the conduit means, and an inlet and an outlet for treating iiuid to the shell.

The outer surface of one section of the header may have two surfaces formed thereon one planar, the other conical.

The conduit means of an exchanger having two surfaces as described above may be substntially U-shaped, one leg of the U being bent such that when the tube is connected to the one section of the toroidal header the bent portion is substantially perpedicular to the conical surface, and may be pitched radially with respect to the axis of the toroid, i.e., the axes of the tubes being arranged in radial planes with consequent radial pitching of corresponding holes through the one section of the header.

In a modification one section of the toroidal header may be provided with one plane surface from which the tubes extend perpendicularly.

Preferably in this modification the pitching of the tubes is triangular, the hole through the header being arranged at the intersections of a triangular lattice frame-work.

One embodiment of the present invention will now CIK be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a sectional side elevation of a heat exchanger.

FIG. 2 is a sectional plan view through section II-II of the heat exchanger of FIG. 1.

FIGS. 3, 4, 5 and 6 are sectional end views through III- IIL IV-IV and VI-VI respectively of FIG 1. in the direction of the arrows.

FIG. 7 is a sectional side elevation of a modified form of the heat exchanger of FIG. 1.

FIG. 8 is a sectional plan view through section II--II of the heat exchanger of FIG. 7.

FIGS. 9, 10 and 11 are sectional end views through -IIL-III, IV--IV and V--V respectively of FIG. 7 in the direction of the arrows.

FIG. 12 is a sectional side elevation of a modified form of the heat exchanger of FIG. 7.

FIG. 13 is an end view of the heat exchanger of FIG. 12 in the direction of the arrow II.

FIG. 14 is a sectional end view through III- III of FIG. 12 lin the direction of the arrows.

Throughout the figures, similar parts are referred to by similar numerals.

Referring to FIGS. 1-6, a heat exchanger of the shell-and-tube type for use, for example, in the heating of feed water passing to a boiler comprises a cylindrical shell 10 closed at one end by a domed plate 30` and provided at its other end with a header I1 from which the tubes 2 of the exchanger extend into the shell 10i. The heat exchanger is arranged vertically with the header 1 at the lower end.

The header 1, which is of substantially toroidal coniguration with an annular bore 28 therein, is made in two parts 1a, 1b the toroid being split by an imaginary frusto-conical surface containing the centre line of the bore 28.

The top part 1a of the toroid serves in effect as the tube plate and is machined to form two surfaces, an outer sur-face 3 substantially perpendicular to the axis of the toroid and an inner `surface 4 angled to said axis to form a conical surface. Both surfaces are drilled to suit the arrangement of tubes and are provided with bosses (not shown) onto which the tubes are welded.

The tubes 2 of the heat exchanger are of the U or hairpin type, one leg 40, however, being bent inwards at its free end 41 such that, on attachment to the top half 1a of the header, this end 41 of the tube is perpendicular to the inner conical surface 4. The tube pitching is radial with respect to the axis of the toroid i.e., the axes of the tubes lie in radial planes.

The bottom part 1b of the toroid is attached to the top half 1a by annular welds 5 and 6 to form the complete header 1 and incorporates inlet 7 and outlet 8 feed branch pipes and one or more manholes 29 to provide access during construction or for subsequent inspection and repair. An annular baffle 9, dividing the bore 28 of the header 1 into two annular sections 36, `37 is provided, the section `36 serving for receiving the incoming feed water to be heated and the section 37 serving for receiving the heated feed water prior to discharge from the header 1 via outlet 8. An aperture (not shown) in the baiile plate 9 enables the inlet 7 to be -in communication with the section 36. Throughbores (not shown) in the part 1a communicate the inlet 41 and outlet 39 ends of the tubes with the sections 36 and 37 respectively..

The complete toroidal header 1 is attached to the shell 10 of the heat exchanger by circumferential Iweld 11 and a plate 12 is attached by welds i13 across the centre of the toroid to form a closed vessel.

The shell n10 is itted with a branch 15 for admitting the heating uid which may be, for example, steam, this branch 15 being positioned near the header 1, and outlets Patented Oct. 29,V 1968 18, 19 for non-condensible gases are also provided at the side top of the shell respectively. An outlet 16, or drain, for condensed steam is fitted to the plate 12 welded across the centre of the toroidal header 41.

Cross flow of the heating fluid is maintained in the shell by means of bafiies, and, on account of the bend in the tube legs, two types of baies are necessary. The baffles 20 are simply plates drilled to conform to the tube pattern and fitted by passing the unbent legs 44 of the tubes through the appropriate holes in the bafiies. The bafiies 21 are necessarily of a different design due to the bend in the legs 40 of the tubes and are therefore built up from segments which can be fitted between the tube legs and are held in position by rings 22. Longitudinal spacing of bafiles 20 and 21 is achieved by spacer rods 24 which serve also to support the baffles and tubes.

The shell is fitted with partition 45 `attached to the shell and the header and dividing the shell into three sections, a steam desuperheating section 26, a steam condensing section 31 the largest of the sections, and a condensing drain cooling section 27. The steam inlet branch opens into the steam desuperheating section 26, the partitions 45 having apertures (not shown) to permit the flow of heating iiuid (steam) from the desuperheating section 26 to the steam condensing section 31 and from the section 31 to the condensate drain cooling section 27. Additional apertures (not shown) are provided in the section 27 to enable the condensed heating fluid to pass to the drain outlet 16. The sections 26, 31 and 27 are so arranged that the feed water in the tubes 2 is successively heated by heating uid of increasing temperature as it flows through the shell.

In operation of the `heat exchanger, superheated steam serving as the heating uid is passed into the desuperheating section 26 whence it passes to the condensing section 31, the baffles 20, 21 ensuring cross flow of the steam through the condensing section 3t1 and consequently a through circulation of the steam therein. The steam condenses in the condensing section 31 and the resulting condensate passes to the drain cooling section, whence it passes to the drain outlet. The feed water is fed to the inlet section 36 via inlet 7 and passes into the tubes 2. The feed water is first heated `by the condensate in the drain cooling section 27, the coolest of the heating uid, then by the mixture of steam and condensate in the condensing section 31 and finally, before the feed water passes from the shell, by the superheated steam in the desuperheating section 26. The heated feed water passes into the outlet section 37 and thence to the outlet 8.

`Referring to FIGS. 7-11, in a modification of the above embodiment the part 1a of the toroidal header 1 is machined to form only one fiat surface 32, said surface being perpendicular to the axis of the toroid. Conventional U-tubes 2 can thus be used, no extra bends being required in the legs, and the pitching of the tubes can be triangular i.e., the throughbores on the header 1 for receiving the tubes being arranged at the intersections of a triangular lattice frame-work (see FIG. 9).

The bore 28 of the header is provided with a fiat 33 such that this section of the bore is parallel to the machined surface 32 of the header 1 the remainder of the bore 28 being part circular.

In this modification, the inlet 15 for admitting steam and outlet 16 or drain for the condensed steam are both provided on the shell 10 adjacent the header 1 and are substantially diametrically opposed. Two bafiies 9, positioned in the bore 28, divide the bore 28 into two segmental sections 36 and 37 and additional drains 49 and 50 are provided for the drain cooling and condensing sections respectively.

Battles 42 are again provided to maintain cross ow and are of the drilled plate type similar to baffles longitudinal spacing of the baiiies being maintained by spacer rods 24. The shell is also partitioned into a steam desuperheating section 26, a steam condensing section 4 31 and a condensate drain cooling section 27 by partitions 45.

In a ffurther modification as shown in FIGS. 12-14, the spacer rods 43 are dispensed with and in their place a centrally positioned support tube 46 is provided in the shell 10 and extending the length thereof. The baffles 42 and appropriate partitions 45 are attached to this support tube 46, By this arrangement, the tube bundles 2 can be supported independently of the heater shell 10. The support tube 46 is welded to the header 1 and has ports 47 to facilitate the passage of steam in the shell 10. The shell 10 has again, adjacent the header 1, an inlet 15 for admitting steam and an outlet or drain 16 for the condensed steam, and is again partitioned into a desuperheating section 26, a condensing section 31 and a condensate drain cooling section 27. Bafiies 9 (FIGS. 12 and 13, divide the annular bore 28 into segmental inlet section 36 and outlet section 37.

The modified heat exchangers operate exactly similar to the rst described heat exchanger.

The above described heat exchanger is suitable particularly for use in power stations where it is required to pass several million pounds of feed water per hour at pressures in excess of 3000 lbs./in.2. Bly using a toroidal header the bending stresses associated with conventional flat tube plates are avoided and the wall thickness of the header can therefore be relatively small.

Further due to the simple shape of the tubes assembly and maintenance is relatively simple.

The first modification has the further advantages of simpler tubes, bafiies, machining and drilling, and welding, and the second modification has the additional advantage of having the tube bundles supported independent of the heater shell.

What I claim is:

1. A heat exchanger comprising a shell having at one end a toroidal header with an annualr bore therein and comprised of two annular sections, the two pairs of annular adjoining surfaces at which the annular sections are joined being arranged such that they lie together with the centre line of the bore on an imaginary frustoconical surface severing the header, the annular sections being joined by welding at the surfaces to form a unitary assembly, inlet fand outlet ports on the header for fluid to be treated in communication with said bore, conduit means mounted on the header and extending into the shell, the conduit means having inlet and outlet openings in communication with the bore, bafiie plates within the bore to separate the inlet to the conduit means from the outlet, from the conduit means, and an inlet and an outlet for treating fluid to the shell.

2. The heat exchanger as claimed in claim 1 in which the header is provided with one plane surface from which the conduit means, in the form of U-tubes, extend perpendicularly.

3. The heat exchanger as claimed in `claim 1in which the header has two surfaces #formed thereon one planar and the other conical, the conduit means being comprised by U-tubes and connecting with these surfaces, one leg of the U-tube being bent such that when the tube is connected to the header, the bent portion is substantially perpendicular to the conical surface.

4. The heat exchanger as claimed in claim 1, in which steam is used as treating uid for the exchanger and the shell is provided with partitioning connecting with the shell and the header and defining a desuperheating section, a condensing section and a condensate drain cooling section, and the partitioning is arranged such as to ensure flow of steam through the shell via, in order of fiow, the desuperheating section, the condensing section and the condensate drain section with the desuperheating section, and the condensate drain cooling section at the outlet and inlet ends of the conduit means respectively.

5. The heat exchanger as claimed in claim 4, in which the condensing section is provided with spaced battles to achieve a thorough circulation of the steam therein.

6. The heat exchanger as claimed in claim 4, in which a plurality of rods are mounted on the partitioning and extend into the condensing section to support the battles in spaced relationship.

7. The heat exchanger `as claimed in claim 4, in which a tube is mounted on the header and extends into the shell to support the partitioning and the baffles in spaced relationship, ports being provided on the tube to enable the heating fluid to pass therethrough.

8. The heat exchanger `as claimed in claim 2, in which the U-tub'es and the corresponding holes through the header yare pitched triangularly.

9. The heat exchanger as claimed in claim3, in which the U-tubes and corresponding 'holes through the header are pitched radially with respect to the axis of the shell.

10. The heat exchanger as claimed in claim 1, in which the inlet and outlet for treating uid are positioned on the shell and the header respectively.

11. rIlhe heat exch-anger as claimed :in claim v1, in which the inlet and outlet -for treating fluid are positioned substantially diametrically opposed on the shell.

References Cited UNITED STATES PATENTS 2,774,575 12/1956 Walter 16S-160 X 2,990,162 6/1-961 Otten 165-145 X 2,910,275 10/1959 Munro 165-161 2,995,341 10/1961 Danesi 165--161 X 3,020,024 2/ 1962 Lawrence 165--161 X 3,129,697 4/1964 Trepaud 122-34 FOREIGN PATENTS 1,275,736 10/1961 France.

918,246 2/ 1963 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

A. W. DAVIS, JR., Assistant Examiner. 

